[PATCH v2 16/17] intel_iommu: Introduce a property to control FS1GP cap bit setting

[Zhenzhong Duan]

When host IOMMU doesn't support FS1GP but vIOMMU does, host IOMMU
can't translate stage-1 page table from guest correctly.

Add a property x-cap-fs1gp for user to turn FS1GP off so that
nested page table on host side works.

This property has no effect when vIOMMU isn't in scalable modern
mode.

Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>
---
 include/hw/i386/intel_iommu.h | 1 +
 hw/i386/intel_iommu.c         | 5 ++++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/hw/i386/intel_iommu.h b/include/hw/i386/intel_iommu.h
index 650641544c..f6d9b41b80 100644
--- a/include/hw/i386/intel_iommu.h
+++ b/include/hw/i386/intel_iommu.h
@@ -308,6 +308,7 @@ struct IntelIOMMUState {
     bool dma_drain;                 /* Whether DMA r/w draining enabled */
     bool dma_translation;           /* Whether DMA translation supported */
     bool pasid;                     /* Whether to support PASID */
+    bool fs1gp;                     /* First Stage 1-GByte Page Support */
 
     /*
      * Protects IOMMU states in general.  Currently it protects the
diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index 9e973bd710..d7e7354db4 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -3778,6 +3778,7 @@ static Property vtd_properties[] = {
     DEFINE_PROP_BOOL("x-pasid-mode", IntelIOMMUState, pasid, false),
     DEFINE_PROP_BOOL("dma-drain", IntelIOMMUState, dma_drain, true),
     DEFINE_PROP_BOOL("dma-translation", IntelIOMMUState, dma_translation, 
true),
+    DEFINE_PROP_BOOL("x-cap-fs1gp", IntelIOMMUState, fs1gp, true),
     DEFINE_PROP_END_OF_LIST(),
 };
 
@@ -4506,7 +4507,9 @@ static void vtd_cap_init(IntelIOMMUState *s)
     /* TODO: read cap/ecap from host to decide which cap to be exposed. */
     if (s->scalable_modern) {
         s->ecap |= VTD_ECAP_SMTS | VTD_ECAP_FLTS;
-        s->cap |= VTD_CAP_FS1GP;
+        if (s->fs1gp) {
+            s->cap |= VTD_CAP_FS1GP;
+        }
     } else if (s->scalable_mode) {
         s->ecap |= VTD_ECAP_SMTS | VTD_ECAP_SRS | VTD_ECAP_SLTS;
     }
-- 
2.34.1